Bump to WebRTC M120 release

Some API deprecation -- ExperimentalAgc and ExperimentalNs are gone.
We're continuing to carry iSAC even though it's gone upstream, but maybe
we'll want to drop that soon.

webrtc/modules/audio_processing/agc2/rnn_vad/rnn_fc.cc

@@ -0,0 +1,104 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "modules/audio_processing/agc2/rnn_vad/rnn_fc.h"
+
+#include <algorithm>
+#include <numeric>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/numerics/safe_conversions.h"
+#include "third_party/rnnoise/src/rnn_activations.h"
+#include "third_party/rnnoise/src/rnn_vad_weights.h"
+
+namespace webrtc {
+namespace rnn_vad {
+namespace {
+
+std::vector<float> GetScaledParams(rtc::ArrayView<const int8_t> params) {
+  std::vector<float> scaled_params(params.size());
+  std::transform(params.begin(), params.end(), scaled_params.begin(),
+                 [](int8_t x) -> float {
+                   return ::rnnoise::kWeightsScale * static_cast<float>(x);
+                 });
+  return scaled_params;
+}
+
+// TODO(bugs.chromium.org/10480): Hard-code optimized layout and remove this
+// function to improve setup time.
+// Casts and scales `weights` and re-arranges the layout.
+std::vector<float> PreprocessWeights(rtc::ArrayView<const int8_t> weights,
+                                     int output_size) {
+  if (output_size == 1) {
+    return GetScaledParams(weights);
+  }
+  // Transpose, scale and cast.
+  const int input_size = rtc::CheckedDivExact(
+      rtc::dchecked_cast<int>(weights.size()), output_size);
+  std::vector<float> w(weights.size());
+  for (int o = 0; o < output_size; ++o) {
+    for (int i = 0; i < input_size; ++i) {
+      w[o * input_size + i] = rnnoise::kWeightsScale *
+                              static_cast<float>(weights[i * output_size + o]);
+    }
+  }
+  return w;
+}
+
+rtc::FunctionView<float(float)> GetActivationFunction(
+    ActivationFunction activation_function) {
+  switch (activation_function) {
+    case ActivationFunction::kTansigApproximated:
+      return ::rnnoise::TansigApproximated;
+    case ActivationFunction::kSigmoidApproximated:
+      return ::rnnoise::SigmoidApproximated;
+  }
+}
+
+}  // namespace
+
+FullyConnectedLayer::FullyConnectedLayer(
+    const int input_size,
+    const int output_size,
+    const rtc::ArrayView<const int8_t> bias,
+    const rtc::ArrayView<const int8_t> weights,
+    ActivationFunction activation_function,
+    const AvailableCpuFeatures& cpu_features,
+    absl::string_view layer_name)
+    : input_size_(input_size),
+      output_size_(output_size),
+      bias_(GetScaledParams(bias)),
+      weights_(PreprocessWeights(weights, output_size)),
+      vector_math_(cpu_features),
+      activation_function_(GetActivationFunction(activation_function)) {
+  RTC_DCHECK_LE(output_size_, kFullyConnectedLayerMaxUnits)
+      << "Insufficient FC layer over-allocation (" << layer_name << ").";
+  RTC_DCHECK_EQ(output_size_, bias_.size())
+      << "Mismatching output size and bias terms array size (" << layer_name
+      << ").";
+  RTC_DCHECK_EQ(input_size_ * output_size_, weights_.size())
+      << "Mismatching input-output size and weight coefficients array size ("
+      << layer_name << ").";
+}
+
+FullyConnectedLayer::~FullyConnectedLayer() = default;
+
+void FullyConnectedLayer::ComputeOutput(rtc::ArrayView<const float> input) {
+  RTC_DCHECK_EQ(input.size(), input_size_);
+  rtc::ArrayView<const float> weights(weights_);
+  for (int o = 0; o < output_size_; ++o) {
+    output_[o] = activation_function_(
+        bias_[o] + vector_math_.DotProduct(
+                       input, weights.subview(o * input_size_, input_size_)));
+  }
+}
+
+}  // namespace rnn_vad
+}  // namespace webrtc